A good example is our blue cotton shirt with a touch of elastane. It is easy to iron, hardly creases and has soft interlining in the collar and cuffs. Elastane doesn't like high heat, so use a medium setting and very little steam on the details.
Knitted shirts are a separate case. Our white shirt in mercerised cotton knit creases less and is easier to iron, because mercerisation strengthens the fibres. Knit fabric does stretch, though, so guide the iron with light pressure and don't pull the fabric, or you will stretch it out of shape.
Steam relaxes the fibres and works well on large panels. The collar and cuffs, however, are reinforced with interfacing, which softens and loses its even shape with too much steam and heat, so use steam sparingly there. Dark fabrics, polyester blends and fabrics with a satin sheen also take on shiny marks easily. Ironing on the reverse or through a thin cotton cloth helps.
Vertical steam, from an iron with that function or from a garment steamer, won't replace ironing, but it is a good way to refresh a shirt that was already ironed and has small creases across the stomach or at the elbows after a day at the office. When you travel without an iron, hang the shirt in the bathroom, run a hot shower for a few minutes and leave the shirt in the steam, away from the spray. You won't press a collar this way, but suitcase creases will soften noticeably. The same trick helps you refresh a jacket without ironing.